With the rapid growth in communications technologies and the increased demand of network users for improved signal speed and reliability, network operators are faced with a constant need to upgrade network performance. The upgrades may be the result of improved technology or the availability of expanded system features. Other than in the case of generation changes where an entire system is replaced, these system upgrades are provided incrementally; generally through the retrofit of certain elements of the network circuitry with improved designs of those elements. With modular equipment, where function is often segregated into individual modules, the new design features can be installed in new version modules which are form and fit compatible with those of the existing installation.
There are, however, certain improvements which necessarily compromise form and fit compatibility, such as where a new design expands a particular function, requiring expanded signal connectivity to a module. This expanded connectivity can arise from a need for a greater number of input data sources or for added output load requirements. In these instantances the existing plant wiring is the bottleneck and some manner of plant wiring modification is required. This of course increases the cost of retrofit and may jeopardize the form and fit of the existing installed equipment. With changes in signal protocols and improvements in communications technologies, the frequency of occurrence of this type event is increasing. It is desirable, therefore, to provide a means to retrofit these type improvements into existing systems without the need for plant modifications.